Field of the Invention
The present invention relates to a circuit configuration for burn-in systems using boards for testing modules disposed like a matrix in the boards, in which the modules in the boards can be connected to input/output channels and can be activated in groups by scan signals.
In the testing of burn-in systems, that is to say systems in which modules are checked for freedom from defects under high-temperature conditions on the order of magnitude of 130.degree. C., and which have a small number of input/output channels for the modules, the number of modules per board or test panel is limited not only by a base size of the respective modules but also by a number of available scan signals. Scan signals or "Enable" signals are used in testing burn-in systems for the purpose of activating a group of modules to be tested for evaluation.
In testing burn-in systems, it is virtually always the case that the maximum possible number of input/output channels of those systems is used. An example that may be mentioned is a burn-in system having 64 input/output channels. If modules with 16 data inputs and/or outputs are tested in such a burn-in system, then it is thus possible to evaluate four modules ("4.times.16=64") in parallel.
However, in such a testing of burn-in systems, the number of scan signals is likewise limited and is at most about 32 to 40 signals depending on the system. Thus, it is then possible to test 160 modules ("4.times.40") in one board, with the result that a maximum board density of approximately 160 modules is given in that case.
On the other hand, in the case of modules with 4 or 8 data outputs, that is to say in the case of "x4" or "x8" organized modules, the board density, limited by the base size, is about 256.
Previously, for the individual module configurations, boards adapted to the requirements of those configurations have been developed in each case especially for each configuration. Since different configurations accommodated in one type of housing have recently been seen, especially in the case of SDRAM modules, the development of separate boards for each of those configurations is extremely complicated. It could be advantageous, therefore, if modules which are accommodated in the same type of housing could be tested by using just one board in a circuit configuration for burn-in systems.